Gun Crazy is a Tier 1 skill in Mordecai'sGunslingerskill tree. When using Pistols (both repeater pistols and revolvers) you have a chance to fire 2 shots with each pull of the trigger instead of just 1.

Skill Progression

Notes

This skill doubles the number of projectiles fired, and naturally all weapons get the same benefit. One might assume that Mashers gain a greater benefit, however, this assumption stems from the idea that more bullets are better. Regardless of what gun is shot, damage is doubled if all bullets land in the same place. (Except for corrosive bullets, for which the second bullet does slightly more damage than the first, meaning that corrosive weapons arguably benefit most.)

The second shot fired does not consume any ammo, so it's basically a free shot. The gun only appears to fire once when this is activated, and has equal recoil to normal shots.